Hacking ram boards to support more ram?

Lips2k8 · 01 May 2008, 16:29

I have got my hands on a Amiga 500 with 512 meg fast ram board. it looks very simular to the A502+ as seen on the big book of amiga hardware - infact I would say its a clone of it. Anyway my question is this - the ram chips on the board are socketed - could they be replaced with bigger ones?

alexh · 01 May 2008, 16:31

Nope. There are only enough address lines going to the A500 trapdoor for 512Kbytes of Fast RAM.

To add anymore you'll need to solder wires to the 68000 or Gary chips.

Lips2k8 · 01 May 2008, 16:42

has it ever been done? - could the chips be removed and soldered in as chip ram in the empty spaces on the A500 motherboard?

alexh · 01 May 2008, 16:46

You'd be better off buying a dedicated RAM card with 68000/Gary adapter.

Yes you can fit RAM to the motherboard on some A500's and with a few tracks cut on the board get 1.5Mbytes of RAM (1Mbyte chip and 512Kbyte fast). It really depends on the version of your motherboard.

Lips2k8 · 02 May 2008, 00:33

ok I think I get the jist... forgive my ignorance but what about amiga 1200 ram cards... for example can a 8 meg max be hacked to support a 16 meg simm instead?

Zetr0 · 02 May 2008, 01:03

@Lips2k8

using simple logic circuitry the addressing space on the amiga (a1200) is only 8MB total. this window also sets up the PCMCIA addressing area as well. so with the full 8MB installed in this manner you will lose the use of the PCMCIA.

now if one uses a small portion of that 8MB window and then uses some far more complicated logic you can have a memory controller that will address from 1 to however much ram you make of it as well as any type.

I have been reviewing some controllers and circuits for SDRAM on an Amiga, however the internal CPU (020) is very slow.

There are plans on the internet that would give you a head start on RAM access, its timings, line propagation's is a common head ache in this area as each device on the circuit can imped access speeds as well as slow down access considerably.

RedskullDC · 02 May 2008, 10:35

Hi,

Quote:

Originally Posted by Lips2k8

I have got my hands on a Amiga 500 with 512 meg fast ram board. it looks very simular to the A502+ as seen on the big book of amiga hardware - infact I would say its a clone of it. Anyway my question is this - the ram chips on the board are socketed - could they be replaced with bigger ones?

Check out :
http://aminet.net/docs/hard/2Megram.lha (by yours truly

)

Will give you a circuit for 2 megs in an A500.
Pretty easy to modify a memory card, and run the wires for extra address lines to the GARY chip (as alexh mentioned).

Where did that last 20 years go??

Hope this helps,
Red

Zetr0 · 02 May 2008, 11:04

@RedSkullDC

!!!!that was you!!!!

rkauer · 06 August 2008, 07:11

Just a question, since I'm tempted to do the hack myself (in one of mine A500 r5):

It have the 1Mb Agnus, so all I need is piggy back the RAM chips over the original ones and route the high address line of it to A21 of Gary and "transform" the A501 in a "FAST RAM" expansion?

01 May 2008, 16:29	#1
Lips2k8 Registered User Join Date: Apr 2008 Location: wolverhampton Posts: 51	Hacking ram boards to support more ram? I have got my hands on a Amiga 500 with 512 meg fast ram board. it looks very simular to the A502+ as seen on the big book of amiga hardware - infact I would say its a clone of it. Anyway my question is this - the ram chips on the board are socketed - could they be replaced with bigger ones?

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01 May 2008, 16:31	#2
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,466	Nope. There are only enough address lines going to the A500 trapdoor for 512Kbytes of Fast RAM. To add anymore you'll need to solder wires to the 68000 or Gary chips.

01 May 2008, 16:42	#3
Lips2k8 Registered User Join Date: Apr 2008 Location: wolverhampton Posts: 51	has it ever been done? - could the chips be removed and soldered in as chip ram in the empty spaces on the A500 motherboard?

01 May 2008, 16:46	#4
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,466	You'd be better off buying a dedicated RAM card with 68000/Gary adapter. Yes you can fit RAM to the motherboard on some A500's and with a few tracks cut on the board get 1.5Mbytes of RAM (1Mbyte chip and 512Kbyte fast). It really depends on the version of your motherboard.

02 May 2008, 00:33	#5
Lips2k8 Registered User Join Date: Apr 2008 Location: wolverhampton Posts: 51	ok I think I get the jist... forgive my ignorance but what about amiga 1200 ram cards... for example can a 8 meg max be hacked to support a 16 meg simm instead?

02 May 2008, 01:03	#6
Zetr0 Ya' like it Retr0? Join Date: Jul 2005 Location: United Kingdom Age: 49 Posts: 9,768	@Lips2k8 using simple logic circuitry the addressing space on the amiga (a1200) is only 8MB total. this window also sets up the PCMCIA addressing area as well. so with the full 8MB installed in this manner you will lose the use of the PCMCIA. now if one uses a small portion of that 8MB window and then uses some far more complicated logic you can have a memory controller that will address from 1 to however much ram you make of it as well as any type. I have been reviewing some controllers and circuits for SDRAM on an Amiga, however the internal CPU (020) is very slow. There are plans on the internet that would give you a head start on RAM access, its timings, line propagation's is a common head ache in this area as each device on the circuit can imped access speeds as well as slow down access considerably.

02 May 2008, 11:04	#8
Zetr0 Ya' like it Retr0? Join Date: Jul 2005 Location: United Kingdom Age: 49 Posts: 9,768	@RedSkullDC !!!!that was you!!!!

06 August 2008, 07:11	#9
rkauer I hate potatos and shirts Join Date: Oct 2007 Location: Sao Leopoldo / Brazil Age: 58 Posts: 3,482	Just a question, since I'm tempted to do the hack myself (in one of mine A500 r5): It have the 1Mb Agnus, so all I need is piggy back the RAM chips over the original ones and route the high address line of it to A21 of Gary and "transform" the A501 in a "FAST RAM" expansion?

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